1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus each comprising the electrophotographic photosensitive member. Particularly, the present invention relates to an electrophotographic photosensitive member comprising a surface layer containing a specified silicone resin, and a process cartridge and an electrophotographic apparatus each comprising the electrophotographic photosensitive member.
2. Description of the Related Art
An electrophotographic photosensitive member is required to have sensitivity, electrical properties, and optical properties corresponding to the electrophotographic process used. Particularly, an electrophotographic photosensitive member repeatedly used is further required to have durability against electrical and mechanical external forces applied directly in charging, image exposure, toner development, transfer, and cleaning. More specifically, the electrophotographic photosensitive member is required to be durability against chemical deterioration due to ozone and nitrogen compounds produced in charging, and mechanical and electric deterioration due to discharge in charging and sliding friction of a cleaning member.
Unlike an inorganic photosensitive member, an electrophotographic photosensitive member a relatively soft material containing an organic photoconductive material has insufficient durability against mechanical deterioration. Therefore, various attempts have been made for satisfying this durability requirement.
Particularly, an example of a method of effectively preventing mechanical deterioration to increase durability is a method comprising adding fluororesin particles to the surface layer of the electrophotographic photosensitive member to decrease the friction coefficient of the surface of the electrophotographic photosensitive member. In this method, sliding friction with a cleaning member is smoothed to prevent a strong shear stress from being applied to the surface of the electrophotographic photosensitive member.
However, the fluororesin particles generally have low surface tension, and cannot be easily uniformly dispersed in a resin having relatively high surface tension. Therefore, the use of various dispersion auxiliary materials has been proposed. However, many commercial dispersion auxiliary materials have a complicated structure because of the excellent dispersibility of the fluororesin, and thus secondary agglomerates of the fluororesin cannot be easily stabilized during dispersion. This is a great problem for the surface layer of a very thin electrophotographic photosensitive member having a thickness of about 1 to 100 xcexcm, and is one of the causes for producing blurring or fogging in an image.
In addition, the dispersion auxiliary material traps carriers to cause a variation in potential in some cases.
Accordingly, an object of the present invention is to resolve the problem inherent in a conventional surface layer comprising a binder resin containing fluororesin particles dispersed therein, and provide an electrophotographic photosensitive member comprising a surface layer that contains fluororesin particles uniformly dispersed therein to improve durability after the formation of the electrophotographic photosensitive member, and that exhibits excellent surface lubricity without negatively affecting its electrophotographic properties.
Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus each comprising the electrophotographic photosensitive member.
In order to achieve these objects, the present invention provides an electrophotographic photosensitive member comprising a photosensitive layer formed on a support member, wherein the surface layer of the electrophotographic photosensitive member contains diorganopolysiloxane represented by the following formula (1): 
(wherein R1 to R6 each represent a substituted or unsubstituted hydrocarbon group, B represents a substituted or unsubstituted organic group having a perfluaroalkyl group, at least one D represents a substituted or unsubstituted polystyrene chain having a closed terminal and a degree of polymerization of 3 or more, E1 and E2 each represent a group selected from R1 to R6, B and D, X represents an integer of 0 to 1000, and Y and Z each represent an integer of 1 to 1000).
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments (with reference to the attached drawings).